Line screen question

[teniworks]

I just got word that I have to do the final production work on a package design. I've never had to set up a package before and I plan on talking to the printer before getting into this but, I wanted to ask a couple of questions to you all so that I'm prepared. The printer emailed our AE who was originally in contact with them asking about the design and making sure that it was set up for "line screening for production" and to see the instructions for halftones. So when I read the instructions, they say to set it up as 45-dot line screen and for the best effect for isolated coverage 35-70% screen tint is required b/c it is being printed on corrugated material. And they want to know how the blues have been made up in the file. *Note: I have not seen the actual design file yet b/c the person who has designed it has not sent it over to me.* Can anyone explain to me what the printer is talking about? I was originally thinking of total ink coverage but, that doesn't sound quite right.

[budafist]

I work as the prepress person for a printer and I don't know what they are talking about. That's a worrry since that email was probably sent by that company's prepress person too.

[SpugNothuson]

I would assume they're talking about 45 lpi (lines per inch).

Also anything that is over 70% tint may start to become solid (or blotchy) and anything under 35% may be too sparse for decent effect.

That'd be my guess.

[jimking]

The printer is the one to set the line screen. For example if its a newspaper they would image their plates at 85lpi to 110 or 120lpi. Offset could range from 133lpi to 300lpi. 45lpi, if I'm understanding this correctly would be very grainy or dots spaced very far apart to say the least. 35-70% could be refering to shadow and highlights, maybe?

[jimking]

SpugNothuson beat me to it. :)

[budafist]

We do set up the lpi (here it's 150lpi default or 175lpi for gloss stock with CMYK images) when we send to plates, but that's not what I gathered from Teniworks' post. It sounded like the printer/prepress wanted Teniworks' to sort it at their end.

I'd never talk lpi with my clients, I just send it through as what we need it to be sent as. I'm surprised that the printer would request this.

[CkretAjint]

Only reason I can think they are asking them to do it, is they have SUCH a low quote to print that they omited prepress on their end and cut that cost to offer them a lower quote.... Or they are just lazy.

[SpugNothuson]

It may not be a request to sort out the artwork into a 45lpi screen it may be more of a "just to let you know".

With that low an lpi I'd be making adjustments to artwork so that I could guarantee quality.

[teniworks]

Maybe this will help. This is what the printer wrote in different emails:

"Once the job is completed, we need the illustrator file saved as EPS and send all the linked files and convert all text to outlines and you need to bleed art 1/4 on all the gray areas, the art is to be screened so the dashed lines need to be at least 1 pt thick. The one you sent are only 5 pt. The Bitmap image on the lid needs to be high res and darker in order to hold if jobs to be screen printed."

I think they meant .5pt instead of 5pt.

When you’ve completed the box, please output for line screening. How are those blues made? Please see the attached instructions on half-tones. We’re line screening for production because it will be a less expensive process than 4-color printing, but there are limitations on half-tones.

I am so confused. :confused:

[budafist]

Oh that makes more sense now. The lpi they are using is very coarse so you will basically need to exaggerate everything in order for it to hold.

[teniworks]

exaggerate everything in order for it to hold.

Can you elaborate a little more?

[budafist]

Since the line screen is so coarse, anything small will not be represented well. Therefore text shouldn't be too small as if you were printing for something with say a 150lpi. I can't elaborate too much because we only work in 150lpi and 175lpi here.

Say your 8pt line of text is going to be represented by 45 lines per inch, this is going to look a lot less tight and focused than if that same 8pt light of text were to be represented by 150 lines per inch.

*kind of* like if your 8pt line of text were to be represented with 45 dots per inch instead of 150 dots per inch.

Also referred to as the line screen frequency, this refers to the measure of distance between the rows of dots that make up a halftone screen. Lower line screens are used on rougher, low quality printing substrates (such as newsprint), whilst higher line screens are used for high quality print jobs on smooth art papers.

[Broacher]

>>Since the line screen is so coarse, anything small will not be represented well. Therefore text shouldn't be too small as if you were printing for something with say a 150lpi.<<

If text is a solid, or a mix of a couple of solid inks, size shouldn't be a problem. It's only when you get a screen percentage involved. Likewise with gradients and tints--if the file is vector it will 'clip' those fat halftone dots at the edges (the dots will actually be split along the vector edge). So in general, don't worry about solid edge work, but be very careful about depending on any small areas containing screens (halftone dots).

["Technical" Terry]

The thickness of the line is dependent on the the stock and the <i>d</a>pi of the plate <i>if</i> the line is solid (generally not much concern). If the line is screened or "transparent" you also need to consider the lpi. Here is a gross example of what could happen, but again your text would be very small and the "dot" very large.
http://i99.photobucket.com/albums/l305/Technical_Terry/01.gif

[budafist]

If text is a solid, or a mix of a couple of solid inks, size shouldn't be a problem.

Good point! If you are doing this thing in CMYK, try and make sure your small text is only solid CMY or K.